It makes the argument stronger. This is because it gives you the chance to respond to your reader's objections before they have finished reading. It also shows that you are a reasonable person who has considered both sides of the debate. Both of these make an essay more persuasive.
It is a metaphor for a mature and deeper kind of love. When Romeo sees Juliet, he is struck by her
and goes so far as compare Juliet to a shrine that just goes to show deep his love
for her is. Upon seeing her, he knows
that he has found true love.